black exhaust crap

hey guys, i've seen exhausts shooting out a bunch of black shit when they shift. I never really knew what it was...some sort of carbon shit? anyway i always thought it was gay, well my new car is doing the same thing. i can see it all over the back of the car. how the hell do i stop it from happening?

iv got a similiar problem, my car is clearly running rich, exhaust is black, i can smell a strong smell of petrol is well, not to mention loss of economy. Would it be the Air/Fuel ratio sensor? IF not whats the cause of running rich.

Originally posted by preludebuddy@Nov 18 2004, 10:05 PMhey guys, i've seen exhausts shooting out a bunch of black shit when they shift. I never really knew what it was...some sort of carbon shit? anyway i always thought it was gay, well my new car is doing the same thing. i can see it all over the back of the car. how the hell do i stop it from happening?

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Running rich, If it's only happening during shifting it is possible that the injectors are still pumping fuel in to the intake when the throttle is rapidly closed causing a temporary rich condition at shifting. Oil burning creates a blue smoke, so this is not the cause. You might ask some these tuning hotshots if there is a way to take care of this.

True that, but an engine is much safer running rich (cooler) than running lean (hot).

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Not necessarily true. The excessive fuel in the cylinders washes down the cylinder walls and keeps them from being lubricated as well. Thats one of the reasons that modern fuel injected engines last longer. Older engines had in inefficient choke mechanisms that dumped large amounts of raw fuel in intakes during a cold start. These had to be eliminated for modern autos to meet emission requirments. In a way we can thank government intervention for our modern and efficient fuel injection systems and longer lasting engines.

Okay. Of course we don't know if the thread starter has a stock setup or a modded one... but speaking from my experience with my Si, someone with a turbo'd VW and another person from Boston who was in Road Atlanta two months ago at a World Challenge race in an ITR, running lean is BAD. Running lean in my Si with the wrong Spoon ECU for my car, toasted my exhaust valves badly. In the the VW, datalogging with a wideband O2 sensor caught the problem in time. In the ITR, they lost two engine blocks from running it too lean.

Depending on what's going on under the hood of that car, ECU tuning can correctly solve the A/F problem.

I'd take rich before lean, but it still aint't right. Your motor just might be spitting carbon. My engine with 150k miles, spits black if I drive it hard. Thats just the carbon build up being spit out.

Originally posted by liquid00meth@Nov 20 2004, 01:11 AMI'd take rich before lean, but it still aint't right. Your motor just might be spitting carbon. My engine with 150k miles, spits black if I drive it hard. Thats just the carbon build up being spit out.

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Finally.

Old hondas spit out carbon build up all the time. Make sure that it's black though. My car was spitting out smoke and I thought it was black, but that was because my CEL was on and it was running rich in limp mode. In reality it was blue smoke.

its definately black carbon stuff its spitting out...no blue smoke. the motor has 80,000 miles on it so its not like its old or anything. I'm just gonna have someone check it out. thanks for the input.